Quantitative susceptibility mapping (QSM) is a magnetic resonance imaging technique in where the voxel intensity is linearly proportional to the underlying tissue apparent magnetic susceptibility. This may be useful for identifying certain biomarkers or contrast agents, such as gadolinium, which cause local changes in the magnetic susceptibility. The bulk magnetic susceptibility distribution of tissue in vivo is calculated from gradient echo magnetic resonance phase images. These images may be particularly useful in showing anatomical contrast between white and gray matter in the brain.
The journal article Tang et. al., “Improving Susceptibility Mapping Using a Threshold-Based K-Space/Image Domain Iterative Reconstruction Approach,” Magnetic Resonance in Medicine 69: 1396-1407 (2013) describes a method of improving magnetic resonance imaging qualitative susceptibility maps by using geometric information from the susceptibility map itself as a constraint to overcome the ill-posed nature of the inverse filter. This paper illustrates applying this approach to vessels and other structures with lower susceptibility to reduce streaking artifacts.
The conference abstract Meineke, “Quantitative Susceptibility Mapping using Segmentation-Enabled Dipole Inversion,” Proc. 23rd ISMRM, p. 3321 (2015) (herein “Meineke et. al.”) discloses a QSM reconstruction which uses a binary map to define tissue boundary edges to improve gradient-based edge detection. The US-patent application US2015/0338492 concerns quantitative susceptibility mapping (QSM) in which edge information is employed in an L1-norm regularisation to calculate the magnetic susceptibility image. The edge information is calculated by way of and edge mask.